Technical note: time-resolved immunofluorometric assay for growth hormone in ruminants

Area of Science:

• Biochemistry
• Immunology
• Analytical Chemistry

Background:

• Radioimmunoassays (RIA) have been standard for bovine growth hormone (bGH) measurement but involve radioactive materials.
• There is a need for safer, faster, and equally accurate diagnostic methods in veterinary endocrinology.

Purpose of the Study:

• To develop and validate a noncompetitive, time-resolved immunofluorometric assay (TRIFMA) for quantifying bovine growth hormone (bGH).
• To establish TRIFMA as a reliable alternative to traditional RIA methods for bGH analysis.

Main Methods:

• A sandwich assay format was employed using monoclonal antibodies (mab) against recombinant bGH.
• One mab was immobilized on microtiter plates, and the other was labeled with Europium-152 (Eu3+) as a tracer.
• Assay involved sample incubation, washing, enhancement solution treatment, and time-resolved fluorescence measurement.

Main Results:

• The assay demonstrated high sensitivity (0.1 ng/mL) and a working range of 0.2-200 ng/mL.
• Excellent recovery (approx. 100%) and minimal cross-reactivity with other hormones or species were observed.
• Intra-assay and inter-assay coefficients of variation (CV) were low (4.4% and 10.7%, respectively).
• TRIFMA results showed strong correlation (r2 ≥ 0.93) with RIA, with a conversion factor of 0.62.

Conclusions:

• The developed TRIFMA is a sensitive, specific, and reproducible method for bGH quantification.
• TRIFMA offers significant advantages over RIA, including speed, safety (no radioactive or hazardous chemicals), and reliability.
• This assay is a practical and effective alternative for routine bGH analysis in research and potentially clinical settings.